The present invention relates to a method for making absorbent articles comprising a backsheet layer having a low autoadhesion attachment means. The articles are capable of being folded and releasably affixed to themselves in the absence of a release liner. The articles of the present invention are particularly useful for managing bodily fluids, such as menses, urine, and perspiration. Sanitary napkins, pantiliners, ultrathins, incontinence devices, wound care and the like are included.
Many absorbent articles, especially those designed and configured to absorb vaginal and/or urethral discharge, utilize pressure sensitive adhesive on a backsheet layer to attach the article to a user""s undergarment. To protect the positioning adhesive prior to use, a releasable sheet is generally applied over the adhesive.
Release sheets have a number of disadvantages. The sheets are typically constructed from silicone coated paper, accounting for an expensive component in an absorbent article""s composition. Moreover, consumers find it inconvenient and indiscreet to dispose of the sheet after removing it from the article.
Anderson et al., U.S. Pat. No. 5,459,193, discloses an approach for eliminating a separate release sheet by applying a hot melt adhesive to a garment-facing surface of an absorbent article that exhibits low self adhesion, and then folding the article upon itself. Anderson teaches the use of a high molecular weight S-EB-S (polystyrene-ethylene/butylene-polystyrene) block copolymer to form a positioning adhesive that is able to be removed from itself without destroying the article, while purportedly having superior stay-in-place properties. The adhesive formulation requires an S-EB-S copolymer having a molecular weight of greater than about 200,000.
Anderson also discloses, in its xe2x80x9cBackground of the Inventionxe2x80x9d section, that hot melt adhesives comprised of lower molecular weight block copolymers for purposes of adhering an absorbent article to an undergarment are known. However, Anderson also teaches that such adhesives are have such high self adhesion that the adhesive layers are separable only at the expense of destroying the article.
It has been found that a broader range of polymers can be utilized to make an absorbent article having a low autoadhesion attachment means, so long as the tensile strength of the backsheet layer is of a certain level and the viscosity of the adhesive is controlled within a certain range.
The present invention provides a method for making an absorbent article having a low autoadhesion attachment means for maintaining the article""s position in use. The article is capable of being folded upon itself prior to use, and then unfolded without destroying any aspect thereof. The present invention eliminates the necessity of a separate release sheet to protect the positioning adhesive prior to use. This will eliminate non value-added costs, enhance consumer convenience by reducing the number of steps of use, enhance consumer discretion by eliminating release sheet handling issues such as noise and disposal, and reduce environmental concerns by eliminating a portion of the product from the solid waste stream.
One method provided by the present invention comprises the following steps: providing an absorbent article comprising a backsheet layer having a tensile strength of at least 5 Newtons per 25 millimeter width of material; directly applying a hot melt adhesive to the backsheet layer outer at a temperature of about 130 to about 177 degrees Celsius, wherein the adhesive has a viscosity of less than about 10,000 centipoise during application; and folding the article in a manner such that the article is releasably affixed to itself.
A second method provided by the present invention produces an absorbent article comprising lateral extensions having positioning adhesive thereon, capable of being releasably affixed to the backsheet.